Firefighters are battling three "pockets of fire" near Blenheim this afternoon.
Fire Service southern communication shift manager Brent Dunn said the blazes being treated as suspicious and a rural fire investigator would likely investigate the cause of the blaze.
A spokeswoman for police was unable to confirm whether police would help with the investigation.
Police have advised locals and motorists to avoid the Wither Hills Farm Park, where emergency services were called about 2.30pm.